The plate heat exchanger is a heat transfer device with high heat transfer efficiency, small footprint, easy installation and use, light weight, low fouling coefficient and compact structure. The corrosion of plate heat exchanger mainly refers to the corrosion of plates. Although most of the plates are made of stainless steel sheets, stainless steel has excellent corrosion resistance. However, under some special conditions, the destruction of the passivation film will cause uniform or partial corrosion of the stainless steel sheet. Uniform corrosion and local corrosion are two types of corrosion of stainless steel plates of plate heat exchangers. Common local corrosion is divided into pitting corrosion, crevice corrosion, stress corrosion, wear and abrasion corrosion. Due to the interrelation of various conditions, several different corrosion patterns will appear during the actual corrosion of the plate. It's just that one kind of corrosion caused damage obviously, while other corrosion hasn't reached the level of damaging the plate. In terms of hazards, localized corrosion is much larger than uniform corrosion. It is often sudden and brings disaster to normal production.